Print hammer mechanism



July 7, 1964 M. J. KITTLER PRINT HAMMER MECHANISM Filed Oct. 16, 1961 ATTORNEY United States Patent M 3,139,820 PRINT HAMMER MECHANISM Milton J. Kittler, Bloomfield Hills, Mich., assignor to Holley Carburetor Company, Warren, Mich., a corporation of Michigan Filed Oct. 16, 1961, Ser. No. 145,414 2 Claims. (Cl. 101-93) This invention relates to printers, and more particularly to a print hammer mechanism that could be employed with the type of printer disclosed in US. application Serial No. 138,157, entitled High Speed Printer, and filed on September 14, 1961, in the names of Arvin D. McGregor and James M. Irvine, Jr.

The structure disclosed in the above referenced application included a print drum that had rows of characters to be printed formed thereon, a row of print hammers positioned adjacent the drum and having one hammer for each character in the row of characters on the drum, a continuously rotating multiple lobe cam, and an inter poser system for each print hammer actuated by appropriate print signals in a manner to cause the print cam to simultaneously drive all addressed hammers into the drum. This structure was referred to as a mechanical amplifier system wherein low power electrical signals released the high energy of a mechanical hammer impacting system.

This invention relates to a generally similar type of hammer system which could be made to operate in the printer referred to above. Accordingly, an object of the invention is to provide a mechanical amplifier type print hammer mechanism.

Another object of the invention is to provide a mechanical amplifier type print hammer mechanism employing an interposer system wherein the hammer impacting means operates continuously but the hammers are actually impacted for printing only when the interposer system is in the print position.

Another object of the invention is to provide a print hammer mechanism such as that referred to above, where in the print hammer itself operates both in response to impact and with the assistance of certain spring means.

A more specific object of the invention is to provide a print hammer mechanism wherein the print hammer is of a composite construction.

These and other objects and advantages of the invention will become apparent upon reference to the following specification and the attached drawings wherein:

FIGURE 1 is a schematic illustration of a print hammer mechanism embodying the invention, with the single print hammer and its associated mechanism being in the non-print position;

FIGURE 2 is a fragmentary portion of FIGURE 1 illustrating the initial steps in the print cycle;

FIGURE 3 is a fragmentary portion of FIGURE 1 illustrating the printing hammer mechanism in the final steps of the print cycle.

Referring to the drawings in greater detail, a printer embodying the invention may include a main or other frame member 19 having a cylindrical print drum 12 mounted thereon so as to be either continuously or intermittently rotated in either direction. The print drum may have axially extending rows of characters 14 to be printed formed thereon and adapted by the rotation of the drum to be presented at the printing station 16 for printing on the record strip 18, with a print ribbon 20 being positioned between the drum and the record strip.

A printer embodying the invention may also have an elongated continuously rotating cam 22 mounted on the frame member 10, the cam member having one or more lobes 24.

As already stated above, a printer embodying the m- 3,139,820 Patented July 7., 1964 Vention would be provided with one print hammer assembly 26 for each character in a row of characters on the drum. If there were characters in a row on the drum, for example, there would be 120 hammers 128 positioned side by side and spaced according to the spacing of the characters 14 on the drum.

One feature of the invention is that the print hammer 28 is a composite structure comprised of two separate members, a first member 30 positioned closer to the cam and a second member 32 positioned closer to the print drum 12, the latter member having a relatively hard character impacting surface 34 formed thereon or secured thereto. The members 30 and 32 are connected by a lost motion slot 36 and pin 38 arrangement; in the structure shown, the slot 36 is formed in the member 30 and the pin 38 received in the slot extends laterally from the member 32. The composite print hammer 28 is guided for reciprocating movement along the line AB extending between the axes of the cam and the print drum, respectively, by an suitable means such as rods 40 or other suitable guide members extending along the entire bank of hammers 28.

A spring 42 of any suitable design is positioned in a slot 44 formed in the print hammer member 32 so that the arms 46 and 48 of the spring normally urge the members 3t) and 32 apart to the position shown .in FIGURE 1. Spring 50, which may be anchored to the printer frame 10, normally urges the composite print hammer 28 to ward the cam 22 against the stop 52.

It is apparent, since each individual print hammer is made up of two separate members, that means such as spacer plates could be employed to maintain the individual print hammers and their associated springs apart and in assembled relation, as in the case of the construction disclosed by the above referenced application.

A cam follower 54, which is mounted on the leaf spring 56 having the other end thereof secured by means of a screw 58 to the printer frame It), is provided for each composite print hammer. The free position of the cam follower may be adjusted by means of a screw 69, one possible adjustment being such that the follower 54 barely engages the circular edge of the cam 22.

The mechanism associated with each individual print hammer also includes a solenoid 62 secured in any manner to the printer frame 10 and having an axially movable core with a suitable rod or pin 64 extending toward the space 66 between the cam follower 54 and the member 30 of the composite hammer 28. The rod has a ball 68 or other enlargement formed in the free end thereof, the width of which may be almost the width of the space 66 between the cam follower 54 and the member 30 of the composite hammer when they are in the position shown in FIGURE 1. This constitutes an interposer system, and the ball 68 is maintained out of the space 66, as shown in FIGURE 1, against the force of the spring 70 positioned between the frame 10 and the spring seat 72 secured to the rod 64 when the solenoid 62 is energized.

It is thus seen from FIGURE 1, which shows one hammer mechanism 26 in the non-print position, that no printing can occur, even though the print drum 12 and the cam 22 may be continuously rotating. In other words, even though the rise or lobe 24 on the cam 22 moves to the dotted line position of FIGURE 1 so that the cam follower 54 is moved to its dotted line position, the cam follower 54 will never engage the print hammer 28 and no printing can occur.

In the printer of the previously referenced application, the interposer system was maintained in the non-print position by a continuously energized holding coil until a print signal was received to energize a pulse coil which cancelled out the magnetic force of the holding coil and 7 3 permitted a spring to move the interposer system to the print position. Likewise, in this construction, the solenoid 62 is continuously energized until a print signal is received to ie-energize the solenoid. When this occurs,

the spring 70 causes the ball 68 or other member formed on the end of the rod 64 attached to the solenoid core to be moved into the space 66 between the cam follower and the member 30 of the composite hammer. This is shown in FIGURE 2, which illustrates the initial positions of the parts of the print hammer mechanism 26 during a single print cycle.

It will be seen in FIGURE 2 that the rise 24 on the cam causes the cam follower 54 to strike the ball 68 which has been previously positioned in the space 66. Depending upon the resiliency and other characteristics of the rod 64 and other hammer parts, the spacing of these parts and other design details, the striking of the ball 68 will either push or impact the member 30 of the composite hammer 28 to the dotted line position of FIGURE 2 so that the pin 33 engages the end of the slot 36 closest to the cam 22, the spring 50 is deflected to its dotted line position and the spring 42 normally holding apart the two members of the composite print hammer 28 is compressed to its dotted line position. At this time, the member 32 of the composite print hammer closest to the print drum 12 has not yet moved to impact the character 14 on the drum.

The final steps of the print cycle are shown by FIGURE 3, wherein the rise 24 on the cam 22 has already passed the cam follower 54 so that the latter has returned to its non-print position against the adjustment screw 60. The interposer ball 68 on the rod of the solenoid has been again removed from the space 66 between the cam follower and the member 30 of the composite print hammer due to re-energization of the solenoid. .The member 30 of the composite print hammer has not moved from its FIGURE 2 position but the spring 42 normally holding the two parts of the print hammer apart has been re-extended to drive the member 32 of the print hammer into a character 14 on the print drum 12.

The final step of a single print cycle would be for the springs 42 and 50 to return the composite print hammer to the non-print position shown in FIGURE 1, and no further printing would occur until the cycle described above is repeated, the cycle being initiated by a signal to print resulting in de-energization of the solenoid.

In the construction shown and described, the print drum 12 is an elongated cylinder having rows 14 of identical characters, and the print cam 22 is an elongated cam at least as long as a row of characters formed on the drum. The printer frame would also be an elongated member extending subsequently along the entire length of the drum. There would be one complete hammer mechanism 26the solenoid 62 and ball 68, the cam follower 54 and its adjustment screw 60, and a composite hammer including the members 30 and 32 and the springs 42 and 50-for each character in a row of characters on the drum.

Whether the hammer actuation is due to the cam 22 actually driving the hammer 28 against the drum 12, a free projectile type of action due to the cam 22 impacting hammer 28 or any combination of these actions together with the forces of the springs 42 and 50, would of course depend upon the details of construction of the parts involved. The main feature of the invention is that a low power print signal causing the solenoid 62 to be de-energized releases higher energy mechanical forces which directly cause the printing. This low electrical power design reduces the cost of a printer and results in many other advantages, such as providing a printer with low radiation noise.

While but one embodiment of the invention has been disclosed, it is apparent that modifications may be made within the scope of the appended claims.

What I claim as my invention is:

1. In a printer having a frame member, a rotating drum having characters formed thereon and a rotating cam, a print hammer mechanism adapted for actuation on a line between the axes of said cam and said drum, said hammer mechanism comprising a spring-mounted cam follower, a print hammer assembly spaced from said follower, a fixed stop intermediate said follower and said print hammer assembly, and an interposer device adapted to be at times positioned between said cam follower and said print hammer assembly, said print hammer assembly being guided for movement along said line of action and including first and second members connected by lost motion means, first spring means for urging said hammer assembly toward said cam and against said stop, and second spring means for urging said first and second members apart so as to take up said lost motion.

2. In a printer, a combination of a rotatable member having characters to be printed formed thereon, a frame member in which said character bearing member is mounted, an elongated cam member mounted on said frame, said cam member being spaced from and parallel to said character bearing member and being at least as long as a row of characters, and a row of print hammer mechanisms between said cam and said character bearing member, there being one print hammer mechanism for each character in a row of characters, each of said print hammer mechanisms comprising a cam follower, a print hammer and an interposer member adapted to be positioned between said cam follower and said print hammer by a signal responsive means when it is desired to print, the line of action of said print hammers being on the line between the centers of said cam and said character bearing member, each of said print hammers being of a composite construction including a first element for actually striking said character bearing element and a second element secured to said first element through lost motion means and adapted to be struck by said cam follower through said interposer member, first spring means for urging said first and second hammer elements to an extended position, and second spring means for urging said second hammer element toward said cam and against a stop, said signal responsive means moving said interposer member upon an appropriate signal from between said cam follower and said print hammer against resilient means urging said interposer member in the opposite direction.

References Cited in the file of this patent UNITED STATES PATENTS 

1. IN A PRINTER HAVING A FRAME MEMBER, A ROTATING DRUM HAVING CHARACTERS FORMED THEREON AND A ROTATING CAM, A PRINT HAMMER MECHANISM ADAPTED FOR ACTUATION ON A LINE BETWEEN THE AXES OF SAID CAM AND SAID DRUM, SAID HAMMER MECHANISM COMPRISING A SPRING-MOUNTED CAM FOLLOWER, A PRINT HAMMER ASSEMBLY SPACED FROM SAID FOLLOWER, A FIXED STOP INTERMEDIATE SAID FOLLOWER AND SAID PRINT HAMMER ASSEMBLY, AND AN INTERPOSER DEVICE ADAPTED TO BE AT TIMES POSITIONED BETWEEN SAID CAM FOLLOWER AND SAID PRINT HAMMER ASSEMBLY, SAID PRINT HAMMER ASSEMBLY BEING GUIDED FOR MOVEMENT ALONG SAID LINE OF ACTION AND INCLUDING FIRST AND SECOND MEMBERS CONNECTED BY LOST MOTION MEANS, FIRST SPRING MEANS FOR URGING SAID HAMMER ASSEMBLY TOWARD SAID CAM AND AGAINST SAID STOP, AND SECOND SPRING MEANS FOR URGING SAID FIRST AND SECOND MEMBERS APART SO AS TO TAKE UP SAID LOST MOTION. 